From mboxrd@z Thu Jan 1 00:00:00 1970 From: "James Harper" Subject: RE: PoD in other (not GPLPV) drivers Date: Mon, 28 Feb 2011 23:28:44 +1100 Message-ID: References: <291EDFCB1E9E224A99088639C47620228D3EDCA7C9@LONPMAILBOX01.citrite.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Return-path: Content-class: urn:content-classes:message In-Reply-To: <291EDFCB1E9E224A99088639C47620228D3EDCA7C9@LONPMAILBOX01.citrite.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Paul Durrant , George Dunlap Cc: xen devel List-Id: xen-devel@lists.xenproject.org >=20 > I actually have plans to push it earlier because we balloon down quite late at > the moment (off the back of the START IRP in the top level bus driver). We are > reliant upon zero-page sweeping code in Xen to save us from guest crashing up > to that point. >=20 I've modified GPLPV to balloon down at DriverEntry time, which seems to be early enough. Prior to that, memory=3D128 and maxmem=3D1024 was = enough to cause a crash under 2008, basically as soon as I tried to access the registry in DriverEntry. My drivers are using WDF and are therefore loading after the KMDF framework which is going to use additional resources. My backup plan is to write a WDM driver that loads even earlier than that and does the allocation, passing it to the real PV drivers later on, although my concern there is that Windows may not like memory allocated by one driver being freed by another... I've never heard of 'zero-page sweeping code' before... is that a way of xen reallocating a previously touched page if it contains all 0's if we want a page beyond our allocation limit? That might explain why my initial balloon down is so slow! I can tell windows to not zero pages before it gives them to me when I do the initial balloon down... what are your thoughts on that? Although it's unlikely at boot time, in theory they could contain sensitive information and I'm supposed to zero them before handing them back to xen according to the docs. James